But your missing the point man. The Legion doesn't have the ability to do any of those things. They can't lock the Brotherhood out of supplies, the Brotherhood will take them. If Caesar is waiting for reinforcements, then the Brotherhood will strike and wipe out the entire camp. The Brotherhood doesn't have to fight a defensive war. Maybe you've made the mistake of assuming that all the Brotherhood soldiers you see in-game are the only ones there are in the Mojave? Because that isn't the case....Stuff like that can't be built to scale in game...Maybe you haven't noticed, but the NCR's main outpost at McCarran only has about 30 people... The Mojave Chapter is way bigger than what your or I see. Not to mention, they can always receive help from out west.
In the end, The Legion just doesn't have the ability to beat the Brotherhood as I've said. Even if they did do that suicide tactic of sending wave upon wave of people until they eventually overran them, the Legion would lose more than it ever gained on a level which far exceeds the insane. The Legion would lose thousands upon thousand of troops. There would barely be a standing army left and what would Caesar have gained? Nothing..Because they have no use for technology remember...And this doesn't even consider that the Brotherhood could always retreat back into their base and fight another day..
Caesar would never be so foolish to attack the Brotherhood, because he'd lose more than he'd ever gain. But yet you call that victory?
You seem to be assuming some sort of omnipotence here while in game it is said that the brotherhood suffered a loss of 1 against 10 when they fought the NCR.
The NCR is not as callous with the lives of their troops as the legion and so the number of casualties against the legion would no doubt be higher, but the strikes they did make would hurt the bortherhood more as the legion is led by a brilliant strategist.
They would not lose thousands of troops isolating the bunker.
Twenty on every brotherhood soldier, possibly, and that is a loss easily taken when you are fighting a siege war with the hive mentality of the legion troops.
You paint them as gods while in reality they are inbred conservative people not willing to make any decision that has no precedents. They cannot ressuply and they sure as hell cannot outnumber. The moment Caesar surrounds the valley the fight is lost, though the actual siege could take a decade or two.